Use of smokeless tobacco (ST) is increasing in prevalence among young American males and is especially prevalent among those residing in rural areas and those who play baseball. Users typically take up the habit as adolescents, and long-term use puts them at risk of oral cancer. Those who give up the ST habit may exchange it for smoking cigarettes, putting them at risk of lung and other cancers. The goal of the proposed research is to increase ST cessation and abstention among baseball athletes attending rural high schools in California. It will implement and evaluate an innovative team-based intervention that will use dental health care providers and peer team members in its delivery. The intervention is based on Cognitive Social Learning Theory and Diffusion of Innovation Theory and applies a public health perspective by approaching ST users in their environment and attempting to change social norms to effect behavioral change. Thirty rural high schools in California with baseball teams will be randomized to receive the intervention or serve as controls. Briefly, the intervention will consist of a 1-hour interactive group session for each team to discuss harmful effects of ST and face-saving ways to refuse it, a strong peer opinion leader component to endorse behavioral change and an educational session for parents and coaches to gain their support. In addition, ST users will be offered an oral exam and cessation advice from a dentist, a self-help guide for quitting, behavioral counseling by a dental hygienist, and booster sessions to prevent relapse or deal with slips. The specific aims are (1) to tailor ST intervention components to rural high school baseball athletes by conducting structured interviews and focus groups among rural athletes and their parents and coaches and by pilot testing the intervention in a rural high school; (2) to assess the prevalence, patterns and correlates of ST use among rural high school baseball athletes via a questionnaire administered to athletes in both intervention and control schools; (3) to determine the efficacy of the intervention by comparing quit rates, changes in motivation to quit, and changes in ST use behavior at the end of the intervention and 1 and 2 years after the intervention, and (4) to identify the characteristics of rural high school baseball athletes that are associated with quitting use of ST. We expect that the intervention tested in this study will be effective in reducing the prevalence of use of ST among high school athletes and will be applicable to other groups of athletes involved in team sports at the high school and junior high school levels.